The present invention relates to an apparatus and method for folding at least one continuous sheet of flexible and foldable material and more particularly to an apparatus and method for folding at least one continuous sheet of flexible and foldable filter medium.
It has been long known to use forming machinery to form pleats in at least one continuous sheet of flexible material and particularly to form continuous filter medium sheets with pleat forming apparatus. In this regard, attention is directed to such patents as U.S. Pat. No. 4,798,575, issued to P. E. Siversson on Jan. 17, 1989, wherein a continuous flexible and foldable sheet of material is fed from a feed cell between two cooperative scoring cylinders which respectively include pleat forming scoring blades and cooperatively aligned recesses to score the sheets for pleat formation. Each of the pleat scored sheets is moved to an endless conveyor, sprayed and held in pleated, spaced relation by screw elements as it is fed in a longitudinal direction on the conveyor. In the references cited in the foregoing U.S. Pat. No. 4,798,575--namely, U.S. Pat. No. 1,348,846, issued to G. G. Brown et al. on Aug. 10, 1920; No. 3,321,345, issued to S. F. Duncan on May 23, 1967; No. 3,809,199 issued to P. E. Bessiere on May 7, 1974; No. 3,959,056, issued to H. W. Caplan on May 25, 1976; No. 3,998,140; issued to C. M. Andre on Dec. 21, 1976; No. 4,045,012 issued to H. Jakob on Aug. 30, 1977; and, No. 4,128,678 issued to P. E. Metcalfe et al. on Dec. 5, 1978, comparatively complex systems, including comparatively complex scoring, forming and corrugating machinery and a multiple of pleating steps are utilized to provide finished products of pleated materials. Not only is the disclosed pleating machinery in these patents expensive and complex in assembly, operation and maintenance, but the finished pleated products in many instances would not be suitable for the efficient filtering purposes as is herein intended. Such filtering deficiencies would also accompany the complex pleating arrangements as noted and disclosed in U.S. Pat. No. 4,736,518, issued to P. Golden et al. on Apr. 12, 1988 and in U.S. Pat. No. 4,793,051, issued to P. Golden et al. on Dec. 27, 1988, both of these patents teaching pleating material by the pressure of opposed blade carrying jig supports.
By pleating material, particularly filter medium in the filtering arts, it has been possible to obtain a greater filtering surface exposed to a fluid stream flowing in a given area. However, with past pleating arrangements--such as above described--the material often tears or breaks and fractures and the fracture of material fibers often occurs in the pleating process and in the pleating apparatus associated therewith. Further, these past arrangements which have required several pieces of machinery and several separate steps have been comparatively slow and complex in pleating production, expensive in manufacture and assembly and generally cumbersome to modify for different pleat sizing and spacing geometries.
The present invention provides a pleat forming apparatus and method which is straight-forward and economical to manufacture and assemble, which accomplishes material conveyance and folding simultaneously, which allows for ready adjustment to accommodate for differing pleating geometries and which has comparatively minimal undesirable consequences on the material folded into pleats during conveyance--particularly, past occurring wear and tear on the material being folded and pleated.
Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth herein.